Ordnance piece



Feb. 3, 1931. M. MCBRIDE ORDNANCE PIECE Filed March 25, 1927 2 Sheets-Sheet 1 ATTORNEYS.

Feb. 3, 1931. M. M BRIDE 1,790,873

ORDNANCE PIECE Filed March 25, 1927 2 Sheets-Sheet 2 I llllllud!!! I VENTOR.

Q M t- QM A TTORNEYS.

Patented Feb. 3, 1931 t i 30 j 1* t.

LEWIS M. MCBRIDE, OF EDGEWOOD, MARYLAND ORDNANCE PIECE Application filed March 25, 1927. Serial No. 178,358.

(GRANTED UNDER THE ACT OF MARCH 3, 1883, AS AMENDED APRIL 30, 1928; 370 O. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates in general to rdnance and more particularly has reference to a muzzle loading projectile discharging piece. Previous to this time the various types of weapons of this character, generally termed mortars, have been to all intents and purposes improvised pieces and have riot been constructed to attain the maximum of range, extreme accuracy or the utmost rapidity in firing, nor have they had any provision for producing the proper rotations of the proj ectile to insure stable flight.

An object of this invention is to provide a muzzle loading projectile discharging piece adapted to afford the maximum range.

Another object of this invention is to provide a muzzle loading projectile discharging piece having extreme accuracy.

Still another object of this invention is to provide a muzzle loading projectile discharging piece constructed to allow the utmost rapidity in firing.

A further object of this invention is to provide a muzzle loading projectile discharging piece adapted to produce proper rotation of the projectile to insure stable flight.

This invention consists in general of the provision of a muzzle loading projectile discharging piece of a type having the ratio of moment of inertia of barrel to its longitudinal axis, small as regard to the moment of inertiaof the projectile to its longitudinal axis. It comprises a barrel having rifiing adapted to rotate the shell, and provided on the butt with a base cap having locking pins,

' the ends of which fit into slots in a base plate socket. The locking pin in the base cap allows the rotation of the projectile by prevention of counter rotation of the barrel affording a proper rotation of the shell to insure stable flight. The barrel is supported by a loosely fitting collar mounted on a bipod to afford sufficient counter rotation of the barrel to take up any play in the locking pin of the base cap in its slots, so that no displacement of the bi-pod and consequent disforming the subject matter of this invention having a rotating member to secure a relative rotation between the projectile and the barrel, adapted to be definitely extended and locked into the rifling by the initial powder pressure of a propellant charge. The propellent charge is held on a cartridge container mounted on the base of the projectile, having apertures communicating with an ignition cartridge. The ignition-is provided with a primer and held in the container to insure the a uniform combustion and positive ignition of the propellant charge surrounding the container. The propellant charge is made up of waterproof slotted powder disks placed around the cartridge container mounted on the base of the projectile and held by a compression nut having a shoulder adapted to firmly clamp the disks, and a shoulder covering surplus aperture in the cartridge container, insuring great initial pressure of the igniter confined in the cartridge container and allowing-a high contact temperature.

In the drawings, forming a part of this specification Figure 1 is a side elevation partly broken away view of the improved muzzle loading projectile discharging piece.

Fig. 2 is a side elevation fragmentary view of the butt and base portion of the piece.

Fig. 3 is a top view of the barrel showing the formation of the rifling.

Fig. 4 is a side elevation fragmentary view of the base of the projectile.

Fig. 5 is a top view taken on line 55 of Figure 4.

Referring by numerals to the drawings wherein the same elements are designated by the same numerals throughout, and more particularly to Figure 1, I is the butt portion of the barrel having reduced extensions 2, 3, 4 and 5 extending from the breech to the muzzle and provided with internal segmental rifling comprising arcuate grooves 6 and arcuate lands 7. The butt 1 is provided with a shoulder 8 designed to receive a base cap 9 in which there is adapted to be journaled a locking pin 11 designed to protrude from both sides of the cap.

The base cap 9 is designed to be seated in a socket formed 011 a base plate 12 having oppositely disposed vertical slots 13. The pin 11 is adapted to fit in the slots 13, held out by the base cap 9 at a point with the center of curvature of the base plate socket to allow for traversing as well as elevating the mortar. The base plate 12 is secured to an additional base 14, to insure the firm emplacement of the piece.

The reduced extensions 3 and 4 on the barrel are provided with loosely fitting split collars 15 and 16 held together by bolts 17 and 18 and nuts 19 and 21. The collars 15 and 16 are held in line by bolts 22 and 23 and nuts 24 and 25. The collar 15 is designed to embrace a loose fitting sleeve 26 adapted to allow slight rotation around the barrel.

The piece is adapted to be supported by a bi-pod structure bolted to the split collar 15. This structure comprises supporting legs 27 fitted in sleeve 28, having projections at their ends pivotally mounted on a knee 29. Collared spikes 30 are secured on the lower ends of the legs 27 to afford firm fixture, when the piece is emplaced. There are also mounted on the legs 27, sleeves 31 having threaded projections 32 to which are adapted to'be fitted the eyes of a strut 33 held on the projection by nuts 34. The strut is provided in the center with a toggle joint, which in conjunction with the pivotal mounting of the legs 27 is adapted to allow the bi-pod to be folded in transport.

An elevation mechanism 36 having internal bevel gears operated by a crank 37 adapted to adjust a threaded shaft 38 is mounted on a shoulder integral with the knee 29.

The lower end of the shaft 38 is adapted to be fitted in threaded engagement with the elevation mechanism 36, and extends downward through the knee 29. The elevation mechanism is adapted to r tate in a fixed vertical plane by the action of the crank 37 and raise or lower the shaft 38.

The upper end of the shaft 38 is fitted in an end bearing 39 supported by the lower section of the split collar 15. There is also incorporated in the end bearing 39, a traversing mechanism operated by a crank 40 engaging a threaded horizontal shaft, rotating in a yoke on the end bearing 39, and in engagement with an extending portion-of the lower section of the split collar 15. By this provision the barrel may be traversed in a horizontal plane within the limitations of the yoke on the end bearing 39.

The rifling in the barrel 1 as shown in Fig. 3 comprises segmental arcuate grooves and arcuate lands allowing a maximum closure of the rifling band to be hereinafter described, to be obtained and preventing the escape of powder gases around the projectile while in the bore, and the consequent loss of range. The rifling grooves permit the escape of pent air and gases in the mortar when" loaded, thereby reducing the time of travel of the projectile down the bore, and allowing greater rapidity of firing than with smooth bore mortar.

The projectile as shown in Fig. 4 comprises a body portion 41 having a reduced threaded tail portion. 42. In threaded engagement with the tail portion 42' is acartridge container 43 provided with circumferential apertures 44 and 45. The exterior of the cartridge container 43 is threaded to receive a circumferential shoulder 46 and a compression nut 47. The cartridge container 43 is also provided with a collar 48.

A driving disk 49 having weakened p0rtions 51 to allow bending and a tapered shoulder portion 52 is adapted to be secured to the base of the projectile by screws 53.

An inverting locking disk or pressure plate method of securing relative rotation between adapted to rest on the ends of the cartridge container 43.

The butt of the barrel is provided with a stationary striker pin 10 adapted to contact with the primer 61 when the shell is dropped down the barrel.

Slotted disks of waterproof powder 58, having perforations 59 as shown in Figure 5, are placed over the cartridge container 43, the foremost resting on the shoulder 46, andarefirmly clamped thereon by means of the compression nut 47, having a shoulder adapted to cover surplus holes in the cartridge container, when only a small amount of powder disks are employed. This manner of applying a propellant charge insures a great initial pressure of the igniter so confined in the V adjustment of the piece without disturbing the emplacement.

While there is no particular limit to the elevation in mortars with barrels having smooth bores, in practice a maximum elevation of only slightly more than 80 is employcd, and whereas the projectile will tumble irrespective of the elevation in a smooth bore mortar, the present piece may be elevated to an upper limit of approximately 65 and still produce the stable flight of the projectile.

' It has been found, however, that a rotating shell is unstable and liable to tumble beyond this value, and that also the irregularities in drift tend to cause inaccuracy.

As the elevation is limited the range is consequently limited with a selected velocitv and for that reason to cover the whole field of fire, the provision of the powder disks to vary the propellant charge is made so that by adding any specific number of disks, the selection of a series of velocities is allowed, each of which may cover a limited part of the field. To cover a whole field of fire, it is necessary therefore to select a series of velocities, each of which will cover a limited part of the "field. This purpose, is accomplished in this invention by the provision of a means for varying the powder charge inasmuch as a single. fixed. or unit charge due to the limits of elevation cannot be employed with a rotating shell to cover the entire field of fire.

The variation ofithe powder charge is accomplished by the use of slotted disk type powder suitably arranged in bundles to provide the necessary increments which may be readily removed to proyide the required amount of propelling charge for any particular zone.

Presuming for calculation that the barrel weighs four times as much as the shell, so that a ratio for example of four to one exists,

their moments of inertia are in the ratio of seven to one. The maximum torque exerted to give theprojectile a proper rotation of stable flight, which is approximately one hundred revolutions a second, during the time the powder charge is acting, which is about.

and time.

the shell, it is absolutely .essential that it a be kept from rotating by locking the base cap 9 to the base plate socket 12, or by some other means, and to prevent its rotation it requires a torque of thirteen thousand pound inches. In the present design this is achieved by the pin 11 extending through the base cap 9 and resting in slots. 13 provided in the base plate 12. These pins are located approximately two inches from the axis, so that each are to get a sheering stress of 3,250 pounds, neglecting the small torque of the friction of the base cap. As the torque equals the product of moment of inertia and angular acceleration. as the projectile and the barrel are subjected to the same torque and as their moment of inertia are in the ratio of one to seven, the free angular acceleration of the barrel would be one seventh that of the shell. As the torque acts for the same time on each and as rotational velocity is the product of angular acceleration and time, the rotational velocity of the barrel would be one seventh that of the shell. The angle turned then in any time is the product of rotational velocity The barrel would therefore turn through one seventh the angle that the shell turns, while going through the bore, if the barrel was not secured against counter rotation as provided.

Pieces of this character of the smooth bore thousand yards as the greatest effective range,

whereas this mortar has in practice demonstrated a range of 2,285 yards with the same propellant charge and the same weight of projectile and by slightly increasing the propellant charge will consistently give 2,500

yards elfective range to 2,750 maximum.

range. L

The piece is supported in a particular manner, inasmuch as the provision of its rotation in counter direction to the rotation of the tail is concerned, and insofar as this is effected in combination with the change in elevation of the mortar of the piece for different ranges is concerned, and also insofar as slight rotation of the play ofthe barrel is concerned. It may be mounted, however, in any manner otherwise allowing the barrel to be placed at such an angle with the horizontal that the projectileinserted in its muzzle, will fall or slide from the muzzle to the breech of the barrel by the gravity exerted by its weight. The projectile is provided with an expansible locking driving disk attached to the rear end of its body and carrying a propelling charge, an ignition, and a primer, supported on its base, is inserted into the muzzle of the piece and allowed to slide by the force and gravity exerted on its weight to the breech of the barrel. Simultaneously when the projectile reaches the limit of its downward travel in the barrel, the firing pin in the body of the barrel is struck by the primer of the base on the projectile causing it to detonate and the ignition charge to ignite the propellant charge.

The expansion of the propellant charge simultaneously inverts the locking plate. extending rific bend or driving disk into the grooves of the rifle and locking it in position, so that the projectile to which the disk is rigidly attached is caused to rotate relative to the barrel as the projectile is forced upward by the pressure of the expansion gas on its base, and as the barrel isprevented from rotating in a counter direction the shell is ejected from the muzzle with the proper rotation to produce stable flight.

Great rapidity of firing at any range within the limits of the piece may be obtained, the only limit to rapidity being the gravity loading time, which will vary with the ele-' vation, and the personal equation.

There is accomplished by this invention an improved muzzle loading projectile discharging piece having advantages over the old type of smooth bore mortars previously used, by

. the provision of means for rotating the projectile and varying the propellant charge to obtain the maximum of range possibilities,

extreme accuracy and allowing the utmost rapidity of firing.

While I have herein shown and described the specific physical embodiments of my invention, it is to be understood that this is to be taken merely as an example of possible modifications, which may be included within the scope of my invention, and hence I do not intend to be limited to the particular structure shown, except insofar as such limitations are imposed by the appended claims.

I claim:

1. A projectile for a muzzle loading mortar, comprising a base portion having a reduced coaxial threaded extension, a tubular cartridge container internally threaded at one end and screwed on the reduced extension, a band having a rearwardly projecting flange and a central aperture fitted over the cartridge container against the base of the projectile, a disk liaving a forwardly projecting flange on its outer periphery and a central aperture fitted over the cartridge container, its forwardly projecting flange resting against the rearwardly projecting flange on the band, a selective number of powder disks provided with central apertures fitted over the cartridge container, and a cartridge in the container adapted to fire the powder disks through communicating apertures in the container, to drive the disk against the band and expand the same.

2. A projectile for a muzzle loading mortar, comprising a base provided with a reduced coaxial threaded extension, a tubular cartridge container internally threaded at one end and screwed on the reduced extension, a band provided with a central aperture fitted over the cartridge container against the base of the projectile and fixed thereto, the band beingformed with an integral rearwardly extending flange on its outer periphery flush with the periphery of the projectile, a disk provided with a central aperture and a forwardly projecting flange on its outer periphery fitted over thecartridge container with its flange resting against the flange on the band. a selective number of powder disks provided with central apertures fitted over and screwed around the periphery of the cartridge container and a cartridge in the container adapted to fire the powder disks through communicating apertures in the container, to propel the projectile and flatten the disk to drive the flange of the band outwardly .to expand the same.

In testimony whereof I aflix my signature.

LEWIS M. MCBRID 

